docs: def use(ctx, shortcut):
      """Use a shortcut."""
      git_dir = current_git_dir()
  
      if git_dir is None:
          output(NOT_GIT_REPO_MSG)
          exit(1)
  
      repo_root = os.path.dirname(git_dir)
  
      config = get_config(repo_root)
  
      try:
          use_shortcut = config.shortcuts.get(shortcut)
  
          while use_shortcut.extends is not None:
              base = config.shortcuts.get(use_shortcut.extends)
              use_shortcut = base.extend(use_shortcut)
      except config.shortcuts.DoesNotExist as err:
          output('{}\nAvailable shortcuts:'.format(err.message))
  
          for s in config.shortcuts:
              output(s.name)
          exit(1)
      else:
          options = use_shortcut.options
          for flag in use_shortcut.flags:
              options[flag.replace('-', '_')] = True
  
          options_string = ''
          for k, v in sorted(iteritems(options)):
              options_string += ' --{}'.format(k.replace('_', '-'))
              if v is not True:
                  options_string += ' {}'.format(v)
  
          output('#{{dim}}$ therapist run{}\n'.format(options_string))
          ctx.invoke(run, **options)